Copper(ii) ketimides in sp3 C–H amination

Commercially available benzophenone imine (HN=CPh2) reacts with β-diketiminato copper(ii) tert-butoxide complexes [CuII]–OtBu to form isolable copper(ii) ketimides [CuII]–N=CPh2. Structural characterization of the three coordinate copper(ii) ketimide [Me3NN]Cu–N=CPh2 reveals a short Cu-Nketimide distance (1.700(2) Å) with a nearly linear Cu–N–C linkage (178.9(2)°). Copper(ii) ketimides [CuII]–N=CPh2 readily capture alkyl radicals R· (PhCH(·)Me and Cy·) to form the corresponding R–N=CPh2 products in a process that competes with N–N coupling of copper(ii) ketimides [CuII]–N=CPh2 to form the azine Ph2C=N–N=CPh2. Copper(ii) ketimides [CuII]–N=CAr2 serve as intermediates in catalytic sp3 C–H amination of substrates R–H with ketimines HN=CAr2 and tBuOOtBu as oxidant to form N-alkyl ketimines R–N=CAr2. This protocol enables the use of unactivated sp3 C–H bonds to give R–N=CAr2 products easily converted to primary amines R–NH2via simple acidic deprotection.